Popular mummy blogger Sophie Cachia has shared the horrifying experience her son suffered his first anaphylactic reaction.

The mother describes the experience like watching a 'zombie plague' that took 'only seconds'.

Writing forWattle Health, the 26-year-old mum wrote: 'It was 2016 and out little family was living in Adelaide.

'That day I hadn’t really gotten around to organising anything for dinner, but I was stoked to find a pre-made pasta sauce in our fridge ready to go! I whipped up some ravioli and popped on the pumpkin and walnut sauce.'

The woman behind popular blogThe Young Mummyreveals she did briefly wonder if her son Bobby, now three, had ever tried walnuts before but quickly dismissed the thought as he had previously eaten peanuts, almonds and pine nuts without reaction before.

Bobby's reaction started when a spoonful of sauce landed on his arm, but Sophie mistook it for a burn.

'Thinking I was the worst mum ever for allowing my son to burn himself, I quickly cleaned him up and, just as I did, he simultaneously popped a spoonful of sauce in his mouth. No pasta, just sauce,' she wrote.

That’s when things took a horrible turn!

'His mouth started to bubble and mini-hives appeared before I even had time to say ‘CRAP’,' Sophie wrote. 'I could see the hives getting bigger and spreading all over his cheeks, his ears, up the back of his neck and starting to go down his chest. He started to scratch like a dog and cough.'

Cachia reveals that her 'mum' panic quickly set in, and the first thought she had was to call her mother.

She then messaged her husband’s football coach while Jaryd Cachia, who played for the South Australian National Football League at the time, was at training.

Jaryd ran home as he was just down the street, and the couple rushed to the car to race Bobby to the emergency room.

'The panic in these situations is so high that we just went, 'JUMP IN THE CAR!' because together we thought we could get there quicker. In hindsight, this was a TERRIBLE move,' Cachia wrote.

'In those 10 seconds of grabbing my bag, with Bobby under my arm, the most horrific thoughts started going through my head: I’m going to kill my son.'

Have had the best time disconnected from the online world this past week (except today) on our holiday, saying no to work for the first time ever & embracing everyday moments with my little famiglia. Will be continuing to do so in preparation for a huge 2018 ahead. Escaping the chaos & jetting away for Xmas is HIGHLY recommended!!! No car hopping in-out, in-out, and no cleaning up 💃🏻💃🏻💃🏻Much love to everybody out there & I hope you've had a magical day. Back to these gorgeous little thangs (ps: Bobby has nicknamed Florence 'Meatball' and its deliciously cute) xxx 💫👨‍👩‍👧‍👦❤️☀️🍸💃🏻😍

The couple hit traffic and Sophie desperately tried to flag down a nearby police car.

Sophie writes, 'The lump in my throat as I write this is making me feel queasy. I was a maniac. I was screaming at the top of my lungs for cars to move or for the lights to change, even contemplating getting out and running to the hospital (again, my logic in this situation was not great).'

'My greatest fear started to kick in when the choking, vomiting and crying turned to utter silence. Bobby had gone limp. Jaryd said, ‘C’mon buddy. Wake up’. This is when I vomited on myself driving and let out a scream that I didn’t even know was inside of me. I was a desperate mum who had made a bad decision. ‘This is it’, I thought. ‘I’ve killed my boy’.

Finally, the couple reached the emergency room where a nurse who heard Cachia’s screams rushed in to help them.

Cachia said the experience was so traumatic, she 'wouldn’t wish on her worst enemy.'

Bobby was diagnosed allergic to both walnuts and pecans.

'That whole scenario would have all happened in no more than 15-20 minutes,' Cachia wrote. 'If he is to come across walnuts again the reaction will be greater. Perhaps quicker. Perhaps fatal.'

'Luckily for us, we walked out of the hospital that time with a healthy boy and two educated parents.'

Bobby now carries an Epipen, as well as an asthma puffer and Zyrtec drops, wherever he goes.

Well it wasn't smooth sailing that's for sure but we snuck a few laughs & happy memories in there amongst the chaos ❤️Most important thing is that my babies are safe in my arms heading home and our family gets stronger through every experience - good or bad. Thank you Jaryd for always being my voice of reason, my calm breaths, my backbone. Florence & Bobby - my every minute & my every breath is always for you ❤️ ps: I NEED A WINE.